1. Field of the Invention
This invention relates to a zoom lens suitable for a camera for photographic film, a video camera and a still video camera, and particularly to a compact zoom lens of three-unit construction.
2. Related Background Art
In recent years, with the tendency of home video cameras toward compactness and light weight, compactness and lighter weight and particularly, a shorter full length and reduced diameter of the front lens have been required of not only camera bodies, but also zoom lenses.
On the other hand, with the compactness of zoom lenses, demand is increasing for zoom lenses in which the angle of view at the wide angle end covers a wide angle range of the order of 60.degree.-80.degree..
Zoom lenses which have, in succession from the object side, a first lens unit having positive refractive power, a second lens unit having negative refractive power and a third lens unit having positive refractive power and in which the second lens unit and third lens unit are moved to thereby effect zooming are disclosed, for example, in Japanese Laid-Open Patent Application No. 51-56645, Japanese Laid-Open Patent Application No. 51-68244 and Japanese Laid-Open Patent Application No. 63-304218.
These zoom lenses, however, could hardly be said to satisfy the aforementioned requirement, i.e., the requirement for being compact and yet securing a sufficiently wide angle range.